Process of treating tanning solutions



Dec. 30, 1930. A. G. WACKENREUTER 1,736,880

PROCESS TREATING TANNl ING SOLUTiONS Filed April 50,1928

ATTORNEY? Patented Dec. 30, 1930' UNITED STATES PATENT OFFICE ANDREAS GUSTAV WAGKE REUTER, OF CHICAGO, ILLINOIS PROCESS OF TREATING TANNING SOLUTIONS Application filed April 30,

l treating tanning solutions Whereinthe remova'l' o-f the objectionable solids enables the solution-to beconcentrated when prepared for marketingland thisconcentrated form of the tanning solutions may be dissolved freely,

thus being relieved ofthe objectionable solids.

A further :obj ect of myinventionis to provide a process of treating tanning solutions for removing objectionable solids, together *witli mold-and other fungi, which form in the v solutions after hides have been subjected to the solutions.

A further object is to provide a process of treating ta nningsolutions whereby the removal-ofthe objectionable solids will permit a freer absorption or penetration of: the solutions in the hides, whiohgives the "leather 'or hides a stronger fiber and makes the hldes thicker.

tOther objects and advantageswill appear in the following spec1fication,-and the novel features of the inventionwill be p articularly ,pointed out in the appended claims.

.' My invention is illustrated in the accompanying drawings, forming part of th1s ap plication, in which 7 Figure 1 is a diagrammatic v1ew of a. centrifugal apparatus,

" Figure'Q is a diagrammatic view of a condensing chamber, 7 i

Figure 3 "is a "diagrammatic view of a dissolving chamber, and" Figure 4 is a diagrammatic vl'ew'of a vat. My "improved process of treating tanning solutions is carried out substantially'in five 5 stages; that is to say, in the firstlstep a new .or unusedsolution is treated to remove ob- 'jectionable solids therefrom, the second step is EtllGzQOIldBIlSlIl g; of the tanning solution; the

w third step .is thedissolving of-the condensed 'tanning solution:andpreparingit for the sub- -.as thesolution enters the chamber v5.

1928. Serial No. 274,100.

jection of hides; the fourth step is the subjecting of hides in the dissolved tanning solution, and the fifth step is the treating of the used tanning solution for removing other ob- !jectionablesol ids. x

.. There are numerous kinds of tanning sollutions. Bythe various kinds I mean solutions extracted from barks, beans, roots, shrubs, nuts, ,or wood. For illustration let us assumethat quebracho wood is used for forming a tanning solution. This tanning solu -tion is formed by first grinding or chipping the quebracho wood into line bits. These .fine bits'of quebracho wood are then subjected to boiling water. The chips of the wood are boiled for 'asufficient time to extract the tannin from the Wood. The result is a solution.

consisting of from 5 to 20% tannin, non-taninns, and impurltiesin the shape of insoluble res nous matter, together Wfth ,80 to 95% water. This formation of the tanning solution is not a part of my invention.

Incarryingout my invention, I make use of a centrifuge 1 having an inlet 2 provided with a feed pipe 3 extending from a receptacle 4 and communicating with the inlet.

The inlet 2- :communicates with a chamber 5 having an inner wall 6. The chamber 5 is provided with an outlet 7 which communicates with adelivering member 8. The member 8 is provided with an outlet spout 9 for a purpose hereinafter described. 7 The new tanning solution, after it has been allowed to cool to normal temperature, is disposed in the receptacle 4 which is positioned above the Centrifuge or bowl 1. The solution passes gravity through the feed pipe 3 and into-the chamber 5 through the inlet 2. The bowl 1 is rotated by a drive pulley '10 which is operatively connected to the bowl 1 through a driven pulley 11 anda belt 12-. I Thebowl l. is rotated at from fifteen thousandto forty thousand revolutions per minute 'This.revolution of the bowl I imparts a revolving motion to the solution The centrifugal force of the solution .is' from twelve thousand to fifteen thousand times gravity and under pressure of approximately six hundred to one thousandpounds per 00 square inch. The new tanning solution may be passed through the bowl 1 and the ob]ectionable solids removed therefrom at any temperature from F. to 200 F if so desired.

During the centrifugal motion of the solution, the lighter substances, such as the liquid portion of the solution, will retain the innermost portion of the body of the solution as it passes through the chamber, and the solids, such as red tannins, fiber, and other solids, will be forced against the inner wall 6 of the chamber. The continued move= ment of the solution into the chamber 5 forces the liquid portion of the solution, which has been treated, through the outlet 7 and into the delivering chamber 8, where the solution is guided through the spout into a container 13. Therefore, as the solution passes from the receptacle at through the feed pipe 3, the inlet 2, and the chamber 5, the centrifugal motion imparted to the solution in the chamber 5 will force the solids contained in the solution outwardly where they will be packed against the inner wall 6 of the chamber and allow the liquor portion of the solution to pass outwardly through the outlet 7, the member 8, the spout 9, and into the container 13. The solution received in the container 13 is freed from the objectionable solids and these objectionable solids, which are in the form of red tannins, fibers, and other solid matters, are in a plastic form upon the inner wall 6. This matter, which is formed of the objectionable solids, ma be removed from the chamber 5 in any esired manner.

The next step of the process is the concentrating of the liquid or solution taken from the container 13. The liquid taken from the container 13 is disposed in a concentrating chamber 14: which is heated by any suitable heating means 15. The, solu-\ tion is heated within the concentrating chamber until it becomes a compact form such as semi-paste, paste, or a solid. The tanning solution may be retained in this stage of concentration until it is to be made ready for the subjection of hides. lVhile the solution is in the concentrated stage, it is reduced from to in quantity.

The third stage of the process is the placing of the concentrated solution in a dissolving chamber 16 with water. The mixture will consist of fromfi to 20% concentrated solution and from 80 to 95% water. This mixture can be diluted with water at any desired temperature.

The solution is now ready for the hides to be submerged therein. In Figure 4 I have shown a diagrammatic view of a vat 17. The solution from the dissolving chamber 16 is then disposed in the vat 17, covering the hides which are iO be treated by the solution. The solution which was taken from the dissolvstronger fiber.

ing chamber 16 is kept in contact with the hides in the vats 17 for the desired length of time, which is about fifteen days;

The next stage of the process is the taking of the solution from the hides in the vat 17 and placing the solution in the receptacle 4. In this step of the process the used solution is reconditioned so that it may be again used for tanning hides. The use of the tanning solution, which is commonly termed as tan liquor, and its contact with the hides causes not only the formation of lac ic acid producing bacilli, which'is very desirable, but also causes the formation of mold and other fungi, which are not only harmful to the production of good leather, but also destroy a considerable percentage of tannin.

The used solution which is placed in the receptacle 4 passes by gravity through the feed pipe 3 and through the inlet 2 into the chamber 5. The chamber 5 is rotated at from fifteen thousand to forty thousand revolutions per minute. The centrifugal force imparted to the used solution which passes into the chamber 5 forces the objectionable solids '9:

which consist of mold and other fungi outwardly into engagement With the inner wall 6, where the solids will be impacted and held as the liquid portion passes outwardly through the outlet 7 the. member 8, through L the spout 9, and into the container 13. The application of centrifugal force to the used tanning solution, while permitting the lactic acid forming bacilli to be retained in the solution, separates and eliminates the mold and other harmful fungi. This-reconditioning of the solution permits a freer multiplication of the lactic bacili, resulting in a very much improved tan liquor or solution which penetrates the hide more quickly, plumps" it better, and gives the leather a much Furthermore, the centrifugal action imparted to the solution eliminates all insoluble substances and substances which are not leather producing.

The second and third stages, which are the condensing and dissolving stages, may be eliminated and the solution may be taken from the first stage and used in the fourth stage;. i. e., in connection withthe hides in the vat 17. The purpose of the stage two is to reduce the solution into compact form so that it may be readily handled and stowed away until ready for use. Furthermore, the solution in the condensed form may be used more readily in commerce when the solution is prepared in one place and to be used in another.

The purpose of the third stage is to dissolve the condensed form of the solution and prepare it for actual use in connection'with hides} As stated heretofore, the condensed form of the solution may be readily and perfectly dissolved due to the previous removing of the objectionable solids, which, when condensed, tend to prevent the dissolving.

I claim:

1. The herein described steps in a process of treating a tanning solution which consists in submitting the solution to the selective action of hides, separating the hides from the solution, removing solids from the solution, and concentrating it.

' 1o 2. The herein described steps in a process of treating a tanning solution which consists in submitting the solution to the selec tive action of hides, separating the hide-s from the solution, centrifugating the solution to remove the solids, and heating the solution to concentrate it.

Signed at Chicago, in the county of Cook and State of Illinois, this 6th day of April,

20 ANDREAS GUSTAV WACKENREUTER. 

